1. Field of the Invention
The present invention relates to a card-shaped electronic apparatus capable of being inserted into a card slot.
2. Description of the Related Art
Recording/reproducing devices, such as magnetic disk drives, optical disk drives, flash memories, and the like are widely used as external storage devices for computers nowadays. Recently, moreover, computers which have PCMCIA-card slots have spread, especially in notebook-type personal computers. Correspondingly, external storage devices that can be inserted into the card slots of the computers have been developed as removable storage media.
On the other hand, miniaturization of hard disk drives (hereinafter referred to as HDDs) has advanced increasingly. Recently, 1- and 1.8-inch HDDs that are expected to be used as removable HDDs have been developed. They are card-shaped HDDs that can be inserted into PCMCIA-card slots.
The card-shaped external storage devices and electronic apparatuses that can be used in the card slots are generally subjected to shock event, so high shock and vibration resistance are required. In general, however, these apparatuses are not so strong against, and sometimes they are carried in a case that is covered with a shock-absorbing member.
These card-shaped electronic apparatuses are fixed in a card slot during operation, so that external shock to the card slot may cause serious damage such as a loss of information. Accordingly, improvement in the resistance against shock and vibration during operation is very important.
When a card-shaped electronic apparatus is set in a card slot, it is supported only by a connector portion, and there is no other solid supporting portions. Its side edge portions are supported in a substantially free state with a small gap with respect to rails of the card slot. If any heavy shock or vibration applies on the card slot, therefore, there is a high possibility that the front or rear edge of the electronic apparatus collides against the card slot rails.
If this collision occurs, the thin card-shaped structure vibrates with a conventional bending vibration mode. Since card-shaped electronic apparatuses that can be inserted into a card slot, including HDDs, have substantially the same exterior design, they have substantially the same bending mode shape although the mode frequency is various.
Since this bending mode frequency is in a low frequency range such as hundreds of hertz, it is the most critical vibration mode that generates large amplitude if any vibration or shock applies on the electronic apparatus. In order to improve the shock and vibration resistance of the card-shaped electronic apparatus, therefore, it is better to increase the natural frequency of the vibration mode.
In general, however, a card-shaped electronic apparatus is limited in thickness in order to meet the standard requirements of the card slot, so it is difficult to increase the natural frequency enough.
The present invention has been contrived in consideration of these circumstances, and its object is to provide a card-shaped electronic apparatus with improved shock and vibration resistance.
In order to achieve the above object, a card-shaped electronic apparatus according to an aspect of the invention is an electronic apparatus that can be inserted into a card slot having a pair of guide rails opposed substantially parallel to each other. This apparatus comprises: a base in the form of a substantially rectangular plate on which components are mounted and having a natural bending vibration mode; and a cover attached to the base and spreading over the components, the base having a pair of side edge portions configured to be guided along the guide rails, and a plurality of protrusions configured to determine the positions where the base contacts the guide rails through or not through the cover, the protrusions being located individually near positions corresponding to nodes of the bending vibration mode on each side edge portion and projecting in the thickness direction of the base.
A card-shaped electronic apparatus according to another aspect of the invention is an electronic apparatus that can be inserted into a card slot having a pair of guide rails opposed substantially in parallel relation to each other. This apparatus comprises: a base in the form of a substantially rectangular plate on which components are mounted and having side edge portions and a natural bending vibration mode; and a cover spreading over the base, the cover having a pair of side edge portions in contact with the side edge portions of the base, individually, and capable of being guided along the guide rails, and a plurality of protrusions configured to determine the positions where the base contacts the guide rails through the cover, the protrusions being located individually near positions corresponding to nodes of the bending vibration mode on each side edge portion of the cover and projecting in the thickness direction of the base.
A card-shaped electronic apparatus according to still another aspect of the invention is an electronic apparatus that can be is loaded into a card storage portion. This apparatus comprises a base in the form of a substantially rectangular plate on which components are mounted and having a natural bending vibration mode; and a cover attached to the base and spreading over the components, the base having a side edge portion capable of engaging the card storage portion and a protrusion configured to determine the position where the base contacts the guide rails, the protrusion being located near a position corresponding to a node of the bending vibration mode on the side edge portion and projecting in the thickness direction of the base.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.